Enhancement of crystallographic and electrical properties in 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 thin films grown on Pb(Zr,Ti)O3-buffered platinized silicon substrates by sol-gel process

We present here a comparative study of sol-gel-derived 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 (PMNT) thin films about 120 nm in thickness that were, respectively, deposited directly on a platinized Si substrate and on a Pb(Zr,Ti)O3 (PZT)-buffered one, but were both annealed at 750 deg. C in ambient air. It was found that the PZT buffer layer plays an important role in the enhancement of crystallographic and electrical properties of PMNT thin films. The PMNT film grown on PZT-buffered platinized Si substrate showed a nearly pure perovskite structure, while the film without buffer layer contained a big amount of pyrochlore phase. Also, the PZT buffer layer changed the preferred orientation of PMNT thin films from (111) to mainly (110) orientation, and helped to improve the films' densification and microstructural evolution. Coherent with what was observed comparatively in structural characterization, enhanced dielectric and leakage current characteristics were observed in the film with buffer layer. For the PMNT film grown directly on Pt-coated Si substrate, the dielectric permittivity is as low as 570, whereas the value is enhanced to 1200 for the PMNT film with PZT buffer layer. Moreover, the leakage current density of PMNT thin films is reduced remarkably, roughly 4-5 orders of magnitude lower, by introducing the PZT buffer layer.